Spray a 9x13-inch glass baking dish with nonstick cooking spray; set aside. Place gelatin into the bowl of a stand mixer fitted with a whisk attachment. Stir in cold coffee; set aside.
In a large deep stockpot, combine granulated sugar, kosher salt, Hershey’s chocolate syrup, and ½ cup creme de cacao over medium-high heat. Stir until just combined. Clip a candy thermometer onto the side of the pan and allow the mixture to reach 240 degrees, about 10 to 15 minutes; do not stir. Remove stockpot from heat.